Promotional Analysis / Grouping Weeks / Cumulative Total

I'm trying to run a promotional analysis where each customer's promotion is running at a different time frame. I will need to measure the run rate of sales for the time leading up to the promotion vs the actual promotion and see what the incremental lift was. I don't know if the best way to perform this is a formula, measure or grouping. The chart below will add some color.

While a much smaller scale this shows what I need to pull off. For example customer A, B and C all have different timings of the promotion and Customer A is running from week# 201801-201804 while Customer B may be running from week 201803-201807.

What is the best way to group customer and have essentially a time frame for the promotion and non promotion?

Re: Promotional Analysis / Grouping Weeks / Cumulative Total

POS Sales stands for Point of Sale Sales... Meaning just sales: The toal number of sales across that given timeframe.

Yes whether the customer runs promotion or not they will have sales just in theory the promotion sales should be higher.

Yes your understanding is correct 201805-201809 for Customer A is not in the promotion.

Actual promotion is the dates listed that the promotion is running and the rate of sales leading up to the promotion would be all sales outside of the promotion (it needs to be a cummulative running total as well) in order to see the effect of the promtion vs non promotion sales.